System and method for adaptive beamforming for specific absorption rate control

ABSTRACT

A system may include a modifiable mobile device having at least two antennas coupled to fractional amplifiers, with returned power detectors. A beamformer unit provides adaptive beam shaping pattern, and a baseband processor provides beam pattern requirements, wherein the beamformer unit modifies the beam pattern requirements with return loss sampling information to shape the adaptive beam pattern so that a transmitted beam pattern minimizes transmitted power reflected back to the mobile device. A method may include regularly measuring a return power level, if output power is greater than a specific absorption rate level, comparing the return power level to a first threshold, else implementing mobile transmit diversity (MTD), and repeating. If the return power level is greater than the first threshold, implementing a MTD combined with reflection-based beamforming that modifies beam pattern requirements of the mobile device with return loss sampling information to create an adaptive beam pattern.

CLAIM OF PRIORITY

This application claims the benefit of priority, under 35 U.S.C. §119,of U.S. Provisional Application No. 61/240,459, filed Sep. 8, 2009,titled “Adaptive SAR Control With Beam Forming,” the contents of whichis hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to specific absorption rate for a mobiledevice and, in particular, to a system and method for specificabsorption rate control using beamforming.

BACKGROUND

Specific absorption rate (SAR) is an indication of the amount ofradiation absorbed by a user of a mobile device. Absorption levels maybe typically defined and measured by placing a liquid-filled phantomhead, hand, or other emulated body part close to the edge(s) of a mobiledevice while transmitting. Measurements of a rise in the liquid'stemperature provide an indication of the radiation exposure.

Meeting SAR requirements for mobile phones may be addressed by radiationpattern shaping, which is facilitated by the fixed orientationrelationship between the mobile phone's handset and the user's head(i.e., next to the ear). However, there are mobile devices thatexperience variable orientation relationships with the human body, forexample cellular modems. A cellular modem may be packaged as a dongleand can be inserted into a portable computer at many differentorientations based on the configuration of the portable computer's ports—typically there may be a minimum of four orientations.

To meet SAR requirements, dongles may be designed so as not to exceedpredefined SAR limitations in all of its possible orientations. Becausemobile antenna patterns may be hard to control, the conventionalapproach may be to set the antenna radiation limits based on peakradiation points rather than peak radiated averages (i.e., totalradiated power (TRP)). This conventional approach may cause vendors tolimit the maximum power, the maximum data rate, and/or the minimalphysical size of the dongle.

SUMMARY

In one embodiment, the invention may provide a system that may include amodifiable mobile communication device. The modifiable mobilecommunication device may have at least two antennas coupled torespective fractional power amplifiers, respective returned powerdetectors coupled to a transmission path between each of the at leasttwo antennas and respective fractional power amplifiers, a beamformerunit configured to provide an adaptive beam shaping pattern to thefractional power amplifiers, the adaptive beam shaping patternconfigured to shape a transmitted beam pattern to minimize an amount oftransmitted power reflected back to at least one of the antennas, and abaseband processor configured to provide beam pattern requirements tothe beamformer unit, wherein the respective returned power detectorsprovide return loss sampling information to the beamformer unit. Thebeamformer unit may be configured to modify the beam patternrequirements with the return loss sampling information to determine theadaptive beam shaping pattern.

In another embodiment, the invention may provide a method that mayinclude a) measuring a return power level present at antennas of amodifiable mobile communication device at regular time intervals, b) ifan output power of the modifiable mobile communication device is greaterthan a predefined specific absorption rate level, comparing the returnpower level to a first threshold, c) if an output power of themodifiable mobile communication device is less than or equal to apredefined specific absorption rate level, implementing mobile transmitdiversity, and d) repeating steps a-c, e) if the return power level isgreater than the first threshold, implementing a mobile transmitdiversity algorithm combined with a reflection-based beamformingtechnique that provides an adaptive beam shaping pattern that shapes atransmitted beam pattern to minimize an amount of reflected transmittedpower, f) re-measuring the return power level, g) if the return powerlevel has increased, applying a change to a diversity parameter of themobile transmit diversity algorithm based on the results of theevaluating step, h) if the return power level is less than a secondthreshold, repeating steps a-c, and i) if the return power level isequal to or greater than the second threshold, repeating steps e-g. Thereflection-based beamforming technique includes the step of modifying abeam pattern requirement of the modifiable communication device withreturn loss sampling information to create an adaptive beam shapingpattern.

In another embodiment, the invention may provide a method that mayinclude a) measuring a return power level present at antennas of amodifiable mobile communication device at regular time intervals, b) ifan output power of the modifiable mobile communication device is greaterthan a predefined specific absorption rate level, comparing the returnpower level to a first threshold, c) if an output power of themodifiable mobile communication device is less than or equal to apredefined specific absorption rate level, implementing mobile transmitdiversity, and d) repeating steps a-c, e) if the return power level isgreater than the first threshold, implementing a mobile transmitdiversity algorithm combined with reflection-based beamforming thatprovides an adaptive beam shaping pattern that shapes a transmitted beampattern to minimize an amount of reflected transmitted power, f)re-measuring the return power level, g) if the return power level hasincreased, reducing the output power of the modifiable mobilecommunication device, h) if the return power level is less than a secondthreshold, repeating steps a-c, and i) if the return power level isequal to or greater than the second threshold, repeating steps e-g. Thereflection-based beamforming technique includes the step of modifying abeam pattern requirement of the modifiable communication device withreturn loss sampling information to create an adaptive beam shapingpattern.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a block diagram of a conventional communicationnetwork;

FIG. 2 illustrates a block diagram of a conventional mobile radioterminal;

FIG. 3 illustrates a block diagram of a mobile communication device inaccordance with an embodiment of the invention;

FIG. 4 illustrates a block diagram of a mobile communication device inaccordance with an embodiment of the invention;

FIG. 5 illustrates a flow diagram for a method in accordance with anembodiment of the invention;

FIG. 6 illustrates a flow diagram for a method in accordance with anembodiment of the invention; and

FIG. 7 illustrates a flow diagram for a method in accordance with anembodiment of the invention.

DETAILED DESCRIPTION

A system, method, and device in accordance with the invention maycontrol transmitting power and directionality of a mobile device antennaso as to maximize effective radiated power (ERP) towards a desireddirection while maintaining the radiation level below maximum limitsthat may be predefined by SAR requirements.

Beamforming may be used to manipulate antenna radiation patterns to, forinstance, shape beam patterns to keep radiation peaks away from a user'sbody to reduce radiation exposure, thereby reducing the body'sabsorption of radiation. Beamforming techniques may be applied when thelocation of the absorption spots are not fixed in space with respect tothe mobile device, but rather vary with the orientation of the mobiledevice (as an example, when the mobile device is stuck horizontally orvertically into a laptop port).

Adaptive beamforming to shape a radiation pattern clear of an absorptionspot having a non-fixed orientation relative to the radiation source maybe done using a sensing mechanism to identify the spatial orientation ofthe mobile device in real time. Systems and methods in accordance withan embodiment of the invention may incorporate a sensing mechanism thatmay use a change in the reflected power received by an antenna in themobile device to identify absorption spots.

In one embodiment of the invention, a determination may be made todetermine whether the radiation level at an identified absorption spotmay be approaching predefined SAR limits. A procedure may implementtransmit diversity techniques to reduce the amount of the radiated powerdirected toward these spots. A beamforming procedure may perform areduction in the radiated directivity without compromising the averageradiated power of the mobile device, and may maintain a maximumallowable ERP towards receiving stations of an electronic communicationnetwork connected to the mobile device.

Mobile devices that may use beamforming forsignal-to-interference-plus-noise ratio (SINR) improvement and to createa shaped directional transmission pattern. While such functionality maybe generally desirable to improve efficiency, user experience, batterylife, etc., meeting SAR requirements may have an overriding importancethat may need to be met under all conditions including when beamformingfor SINR and other considerations.

Adaptive beamforming may be a signal processing technique that achievesspatial selectivity by using adaptive beam patterns. Adaptivebeamforming may detect and estimate the signal-of-interest by, forexample, data-adaptive spatial filtering and interference rejection.Beamforming may take advantage of interference to change thedirectionality of the array. When transmitting, a beamformer unit maycontrol the phase and relative amplitude of the signal at each antennaelement so as to create a pattern of constructive and destructiveinterference in the transmitted wave front.

Beam steering is different than beamforming. Beam steering may changethe direction of the main lobe of a radiation pattern. Beam steering maybe accomplished by switching antenna elements or by changing therelative phases of the RF signals driving the elements.

Return Loss Variation Detection

Perfectly matching the output impedance of an antenna to free space maybe unobtainable. The antenna mismatch may cause some of the transmittedpower to be reflected back to the power transmitter circuitry. Thisreflection phenomenon may intensify when the radiating antenna is placedclose to an absorbing substance, for example a human body. Two adverseeffects may happen: (i) the human body may absorb radiation; and (2)altering the antenna's impedance moves the antenna match from its designvalues and may cause an increase in the level of power reflected back tothe transmitting circuitry.

A mobile device may include circuitry that may implement mobile transmitdiversity (MTD), which may use two or more transmitting antennas. Forexample, U.S. Pat. No. 7,551,890 to Fenk et al., “Method for Reducingthe Radiation Load by a Mobile Radio Terminal with Directional Emission,and a Mobile Radio Terminal with Directional Emission,” describesreducing the power emission from a mobile station while maintainingtransmission quality requirements by using an antenna with adjustabledirectional characteristics.

FIG. 1 illustrates a block diagram of a conventional communicationnetwork that may include a modifiable mobile communication device 10having antennas 11 a, 11 b. The mobile communication device may transmita signal, or series of signals that may be received by base station 20via antenna 21. Within base station 20 may be feedback generator 22 thatmay evaluate the received signal from mobile communication device 10 andmay provide a feedback signal containing information describing thereceived signal. Base station 20 may transmit the feedback signal forreception by mobile communication device 10. Signal modifier 12 withinthe mobile communication device may evaluate the received feedbacksignal and implement adjustments on the signal transmitted from themobile communication device. Antenna selection, phase and/or powerdifferences may change the direction of a main lobe transmitted frommobile communication device 10.

FIG. 2 illustrates a block diagram of the transmit channel for aconventional mobile radio terminal that may reduce radiation bydirectional emission. Antenna 105 may have controllable directionalcharacteristics. The antenna may be connected to power amplifier 104(PA). The power amplifier may be connected to a radio-frequencytransmitter 102. Baseband processor 101 (BB) may be connected to the RFtransmitter. The BB processor may have outputs that include bit errorrate and received signal field strength information and/or data. The biterror rate and the received field strength information may be inputvariables provided to evaluation unit 103. The output of evaluation unit103 may be connected to antenna adjustment device 106. The antennaadjustment device may provide a control signal to a control input ofcontrollable antenna 105. The evaluation unit 103 may make it possibleto adjust the main lobe direction of antenna 105, via the antennaadjustment device, such that reception and transmission power signalqualities may be optimized.

A mobile device may include circuitry that may monitor the transmittedchannel returned power level. For example, U.S. Pat. No. 7,702,032 toBoos, “Transmitter and Method of Transmitting a Signal,” describes usinga circulator coupled to the output of a transmitter and, for example,monitoring the transmitter output impedance and matching a poweramplifier's impedance to a change in transmitter output impedance.

FIG. 3 illustrates a block diagram of mobile device 200 in accordancewith an embodiment of the invention. Mobile device 200 may be amodifiable mobile communication device that can reduce SAR levelexposure to a user by implementing reflection-based beamformingtechniques that are in accordance with an embodiment of the invention.Mobile device 200 may include antennas 206 a, 206 b connected torespective fractional output power amplifiers 204 a, 204 b. Embodimentsof the invention may have other quantities of antennas and poweramplifiers.

Each antenna may be a single radiating element, or an array of radiatingelements. The radiating elements may be, for example, a monopole,dipole, loop, patch, microstrip, dielectric, or other type of radiatingelement. The output power amplifiers each may be set to an equal powerlevel (e.g., half transmitted power), or to unequal levels as may bedetermined by beamformer unit 203. Respective returned power detectors205 a, 205 b are positioned between the output power amplifiers and theantennas. Although schematically represented as being in-line withfractional output amplifier 204 a, 204 b and antennas 206 a, 206 b, thedetectors need only sample the RF present on the output channels bybeing coupled to a transmission path between the antenna and thefractional power amplifier. Detectors 205 a, 205 b may be, for example,circulators, diodes, crystals, or other solid state devices.

Detectors 205 a, 205 b may provide sampling information to beamformerunit 203. The sampling information may include amplitude and/or phaseinformation of return loss signals present at one or more of antennas206 a, 206 b. This sampling information may be an indication of thematch of the antennas to the free space environment (e.g., scatteringmatrix, impedance mismatch, reflected return signal levels, etc.). Thissampling information may be used in conjunction with beam patternrequirements that may be provided by baseband processor 201 tobeamformer unit 203 to create a reflection-based beamforming patternthat may adaptively shape a transmitted beam pattern to minimize anamount of transmitted power reflected back to the radiating antenna whenmobile device 200 is placed close to an absorbing substance, forexample, a user's body. The adaptively-shaped beam pattern havingreduced power levels, and/or nulls, in a direction of a user's body soas to reduce SAR levels in the user.

The baseband processor may provide control information to radiofrequency transmitter 202 (RF TRX). The control information may includeoperating frequency, power level, and modulated signal information fortransmission. RF transmitter 202 may provide modulated RF signals to oneor more input channels of beamformer unit 203, which may be disposedbetween the RF transmitter and the fractional power amplifiers.

FIG. 4 illustrates a block diagram of mobile device 300 in accordancewith an embodiment of the invention. Mobile device 300 may be amodifiable mobile communication device that can reduce SAR levels in auser by implementing reflection-based beamforming techniques that are inaccordance with an embodiment of the invention. Mobile device 300 may bea modifiable mobile communication device that can reduce SAR levelsexposure to a user by implementing reflection-based beamformingtechniques that are in accordance with an embodiment of the invention.

Mobile device 300 may include antennas 306 a, 306 b connected torespective fractional output power amplifiers 304 a, 304 b. Embodimentsof the invention may have other quantities of antennas and poweramplifiers.

Each antenna may be a single radiating element, or an array of radiatingelements. The radiating elements may be, for example, a monopole,dipole, loop, patch, microstrip, dielectric, or other type of radiatingelement. The output power amplifiers each may be set to an equal powerlevel (e.g., half transmitted power), or to unequal levels as may bedetermined by beamformer unit 303. Respective returned power detectors305 a, 305 b are positioned between the output power amplifiers and theantennas. Although schematically represented as being in-line withfractional output amplifier 304 a, 304 b and antennas 306 a, 306 b, thedetectors need only sample the RF present on the output channels bybeing coupled to a transmission path between the antenna and thefractional power amplifier. Detectors 305 a, 305 b may be, for example,circulators, diodes, crystals, or other solid state devices.

Detectors 305 a, 305 b may provide sampling information to beamformerunit 303. The sampling information may include amplitude and/or phaseinformation of return loss signals present at one or more of antennas306 a, 306 b. This sampling information may be an indication of thematch of the antennas to the free space environment (e.g., scatteringmatrix, impedance mismatch, reflected return signal levels, etc.). Thissampling information may be used in conjunction with beam patternrequirements that may be provided by baseband processor 301 tobeamformer unit 303 to create a reflection-based beamforming patternthat may adaptively shape a transmitted beam pattern to minimize anamount of transmitted power reflected back to the radiating antenna whenmobile device 300 is placed close to an absorbing substance, forexample, a user's body. The baseband processor may provide controlinformation to beamformer unit 303. The control information may includeoperating frequency, power level, and modulated signal information fortransmission.

Beamformer unit 303 may be coupled to the BB processor and disposedbetween the BB processor and respective RF transmitters 302 a, 302 b. ARF output from the reflection-based beamformer may be provided torespective RF output channels coupled to respective RF transmitters 302a, 302 b.

A reflection-based beamformer in accordance with an embodiment of theinvention may be implemented as a processor, a field programmable gatearray, integrated within the BB processor, or implemented as one or moresoftware modules stored in a nonvolatile memory accessible by aprocessor, for example the BB processor.

Mobile devices 200, 300 may facilitate the measurement of normative andexcessive returned power levels, where excessive returned power levelsmay be above SAR recommended levels. The excessive returned power levelsmay be from a mismatch between the antenna(s) and their immediateenvironment, which may indicate the presence of a user's body.

Mobile devices 200, 300 may be used to implement MTD by, for examplebeamforming and/or antenna selection, using at least two antennas, andfeeding each antenna from a fractional (for instance half-power) poweramplifier.

FIG. 5 illustrates Process 400 in accordance with an embodiment of theinvention. Process 400 may be a method for obtaining calibration pointsof returned power levels and thresholds that may be used by areflection-based beamformer in accordance with an embodiment of theinvention. The process may first transmit a signal from a mobilecommunication device with a predetermined diversity parameter value, andmeasure an unloaded return loss value. Measurements may be repeated forother diversity parameter values to obtain a set of unloaded returnvalues. The measurements may then be repeated for the same diversityparameter values to obtain loaded return loss measurements. Whileoperating two or more antennas, a calibration procedure may be asfollows.

Operating at a transmitting power level, for example maximum outputpower, step 401, set a diversity parameter value, step 402 (e.g.,relative phase and/or power weighting). Measure an unloaded return lossat each antenna, step 403. At step 404 a decision may be made as towhether there are additional parameter values (e.g., phase), if thereare additional values Process 400 may return to step 401. If alldiversity parameter values have been measured, Process 400 may continueto step 405.

The mobile device may be subject to SAR testing, by performing steps405-408, which correspond to steps 401-404 except under loadedconditions —i.e., where the antenna is located near an absorbing body.Steps 405-408 may be repeated for each of the diversity parameter valuesand may be repeated for all possible orientations of the mobilecommunication device with respect to the absorbing body. For example, asdescribed above there may be four orientations for a cellular modempackaged as a dongle.

Steps 401-408 may be repeated under a sufficient number of cases toobtain adequate resolution of data points.

The returned power levels of unloaded and loaded returns may be comparedto generate a deviation table of returned power level deltas and/orcalculated VSWR values (using known forward power levels and themeasured return power levels) that are correlated with the SARmeasurements.

A list of not-to-exceed and threshold return level deltas may bederived, step 409, by recording SAR values and returned power levels(loaded returns) under these conditions. The deltas of not-to-exceedreturn power level deltas (dB, dBm, or mW) and/or VSWRs versus diversityparameter values may be presented in a table or list. These data pointsmay indicate when not-to-exceed SAR levels are being approached, and maybe used to determine where to set thresholds for activating ordeactivating correction mechanisms such as reflection-based beamformingand/or transmit power reduction so as to assure operation of a mobilecommunication device within predefined SAR levels. The reflection-basedbeamforming may provide an adaptive beam shaping pattern that may shapea transmitted beam pattern to minimize an amount of reflectedtransmitted power.

Table 1 illustrates a sample table derived from the data points obtainedby Process 400 for phase. A table may also be obtained from data pointsfor amplitude and other diversity parameter values.

TABLE I Sample Exceeding SAR Calibration Diversity Return Parametervalue Loss in Exceeding Frequency (Relative Phase Return Loss in SARtesting SAR (MHz) in degrees) free space (dB) (dB) (dB) 1852.4 36 10 81.1 1852.4 48 10 11 0.5 1852.4 60 10.5 13 1.3 1852.4 72 11 9.6 0.7

Beamforming and Returned Power Correction

FIG. 6 illustrates Process 500 in accordance with an embodiment of theinvention. Process 500 may be a method for return power correction andreducing SAR levels that may be implemented by a reflection-basedbeamformer in accordance with an embodiment of the invention.

During operation of a mobile device, Process 500 may regularly measurethe return power level, step 501. The regularity of these measurementsmay be done constantly, periodically, continually, or at another timeinterval. Monitoring of the return power loss measurements may be doneto determine when to trigger a return power correction mechanism. If anoutput power of a mobile device is greater than the SAR level (maximumoutput power exceeds SAR) and a returned power delta is not greater thanthreshold 1, step 502, a MTD technique without a reflection-basedbeamforming technique may be implemented, step 503. Where threshold 1 isa function of the operating frequency and diversity value, and may beequal to a loaded return loss (SAR testing) minus an unloaded returnloss (free space) plus a back-off margin (dB). Process 500 may obtainthreshold 1 from reading an entry in a lookup table stored in memory,where the lookup table may have the information described with referenceto Table 1, above. After implementing the MTD technique without areflection-based beamforming technique, Process 500 returns to measuringthe return power level, step 501. The reflection-based beamformingtechnique may provide an adaptive beam shaping pattern that may shape atransmitted beam pattern to minimize an amount of reflected transmittedpower.

If threshold 1 is exceeded, step 502, a MTD technique with areflection-based beamforming technique may be implemented, step 504.After the MTD with reflection-based beamforming is implemented, thereturn power is measured, step 505, to determine if there has been anincrease in return power compared to the measurements made previously.

If the return power has increased, an unfavorable result, Process 500continues at step 506, where a large step or skip in the diversityparameter is applied to the output signal by the MTD control. Withreturn power correction, if gradient-seeking algorithms in MTD controlincreases returned power, those phases exceeding SAR at maximum power(large step) may be skipped.

If the return power has not increased, Process 500 continues at step 507where the return power level is measured. In some embodiments the returnpower level may not need to be measured at step 507 if the valueobtained at step 505 is available for use by Process 500 and step 506was not performed.

The returned power level is compared to threshold 2, step 508. Wherethreshold 2 may be, for example, half of threshold 1. Process 500 mayalso use other values for threshold 2, for example threshold 2 may be ata minimum 0.5 dB, or threshold 1 minus 0.5 dB.

If the returned power level is determined at step 508 to be less thanthreshold 2, then Process 500 continues at step 503, where the returnpower correction from step 504 may be turned off. If the returned powerlevel is determined to be equal or greater than threshold 2, thenProcess 500 continues at step 504 where further reflection-basedbeamforming techniques may be implemented.

FIG. 7 illustrates Process 600 in accordance with an embodiment of theinvention. Process 600 may be a method for return power correction andreducing SAR levels that may be implemented by a reflection-basedbeamformer in accordance with an embodiment of the invention.

During operation of a mobile device, Process 600 may regularly measurethe return power level, step 601. The regularity of the measurements maybe done constantly, periodically, continually, or at another timeinterval. Monitoring of the return power loss measurements may be doneto determine when to trigger a return power correction mechanism. If anoutput power of a mobile device is greater than the SAR level (maximumoutput power exceeds SAR) and a returned power delta is not greater thanthreshold 1, step 602, a MTD technique without a reflection-basedbeamforming technique may be implemented, step 603. Where threshold 1 isa function of frequency and diversity value, and may be equal to aloaded return loss (SAR testing) minus an unloaded return loss (freespace) plus a back-off margin (dB). Process 600 may obtain threshold 1from reading an entry in a lookup table stored in memory, where thelookup table may have the information described with reference to Table1, above. After implementing the MTD technique without areflection-based beamforming technique, Process 600 returns to measuringthe return power level, step 601.

If threshold 1 is exceeded, step 602, a MTD technique with areflection-based beamforming technique may be implemented, step 604.After the MTD with reflection-based beamforming is implemented, thereturn power is measured, step 605, to determine if there has been anincrease in return power compared to the measurements made previously.

If the return power has increased, an unfavorable result, Process 600continues at step 606, which reduces the transmit power.

If the return power has not increased, Process 600 continues at step 607where the return power level is measured. In some embodiments the returnpower level may not need to be measured at step 607 if the valueobtained at step 605 is available for use by Process 600 and step 606was not performed.

The returned power level is compared to threshold 2, step 608. Wherethreshold 2 may be, for example, half of threshold 1. Process 600 mayalso use other values for threshold 2, for example threshold 2 may be ata minimum 0.5 dB, or threshold 1 minus 0.5 dB.

If the returned power level is determined at step 608 to be less thanthreshold 2, then Process 600 continues at step 603, where the returnpower correction from step 604 may be turned off. If the returned powerlevel is determined to be equal or greater than threshold 2, thenProcess 600 continues at step 604 where further reflection-basedbeamforming techniques may be implemented. The reflection-basedbeamforming technique may provide an adaptive beam shaping pattern thatmay shape a transmitted beam pattern to minimize an amount of reflectedtransmitted power.

If phase continuity constraints are mandated for the mobilecommunication device's protocol, large steps in the MTD gradient-seekingalgorithm can be turned into normal steps by reducing the maximumtransmitted power by the amount of power exceeding SAR (dB) levels at acurrent frequency and diversity value.

While there have been shown, described, and pointed out fundamentalnovel features of the invention as applied to several embodiments, itwill be understood that various omissions, substitutions, and changes inthe form and details of the illustrated embodiments, and in theiroperation, may be made by those skilled in the art without departingfrom the spirit and scope of the invention. Substitutions of elementsfrom one embodiment to another are also fully intended and contemplated.The invention is defined solely with regard to the claims appendedhereto, and equivalents of the recitations therein.

1-8. (canceled)
 9. A method comprising the steps of: a) measuring areturn power level present at antennas of a modifiable mobilecommunication device at regular time intervals; b) determining that anoutput power of the modifiable mobile communication device is greaterthan a predefined specific absorption rate level, and comparing thereturn power level to a first threshold; c) determining that the returnpower level is greater than the first threshold, implementing a mobiletransmit diversity algorithm combined with a reflection-basedbeamforming technique, the reflection-based beamforming techniqueproviding an adaptive beam shaping pattern that shapes a transmittedbeam pattern to minimize an amount of reflected transmitted power; d)re-measuring the return power level; e) determining that the returnpower level has increased, and applying a change to a diversityparameter of the mobile transmit diversity algorithm based on theresults of the evaluating step; f) determining that the return powerlevel is equal to or greater than a second threshold, repeating stepsc-e until the return power level is less than the second threshold. 10.The method of claim 9, further including the step of obtaining the firstthreshold from a lookup table.
 11. The method of claim 9, furtherincluding the step of calculating the first threshold.
 12. The method ofclaim 11, wherein the first threshold equals a loaded return loss minusan unloaded return loss plus a margin.
 13. The method of claim 9,wherein the reflection-based beamforming technique includes the step ofmodifying a beam pattern requirement of the modifiable communicationdevice with return loss sampling information to create the adaptive beamshaping pattern.
 14. The method of claim 9, further including the stepof skipping phase diversity parameters in a gradient-seeking mobiletransmit diversity algorithm that result in return loss increases. 15.The method of claim 14, wherein if a phase continuity constraint ismandated for the modifiable mobile communication device, a resolution inthe changes to the phase diversity parameter can be minimized by furtherincluding the step of reducing transmitted power by an amount of powerexceeding specific absorption rate levels at a current frequency anddiversity value.
 16. A method comprising the steps of; a) measuring areturn power level present at antennas of a modifiable mobilecommunication device at regular time intervals; b) determining that anoutput power of the modifiable mobile communication device is greaterthan a predefined specific absorption rate level, and comparing thereturn power level to a first threshold; c) determining that the returnpower level is greater than the first threshold, implementing a mobiletransmit diversity algorithm combined with reflection-based beamforming,the reflection-based beamforming providing an adaptive beam shapingpattern that shapes a transmitted beam pattern to minimize an amount ofreflected transmitted power; d) re-measuring the return power level; e)determining that the return power level has increased, and reducing theoutput power of the modifiable mobile communication device; f)determining that the return power level is less than a second threshold,repeating steps a-b, until the output power of the modifiable mobilecommunication device is less than or equal to the predefined specificabsorption rate level.
 17. The method of claim 16, further including thestep of obtaining the first threshold from a lookup table.
 18. Themethod of claim 16, further including the step of calculating the firstthreshold.
 19. The method of claim 18, wherein the first thresholdequals a loaded return loss minus an unloaded return loss plus a margin.20. The method of claim 16, wherein the reflection-based beamformingincludes the step of modifying a beam pattern requirement of themodifiable communication device with return loss sampling information tocreate the adaptive beam shaping pattern.
 21. A method comprising thesteps of: a) measuring a return power level present at antennas of amodifiable mobile communication device at regular time intervals; b)determining that an output power of the modifiable mobile communicationdevice is less than or equal to a predefined specific absorption ratelevel, implementing mobile transmit diversity; and c) repeating stepsa-c, until the output power of the modifiable mobile communicationdevice is greater than a predefined specific absorption rate level; d)determining that the return power level is greater than the firstthreshold, implementing a mobile transmit diversity algorithm combinedwith a reflection-based beamforming technique, the reflection-basedbeamforming technique providing an adaptive beam shaping pattern thatshapes a transmitted beam pattern to minimize an amount of reflectedtransmitted power; e) re-measuring the return power level; f)determining that the return power level has increased, and applying achange to a diversity parameter of the mobile transmit diversityalgorithm based on the results of the evaluating step; g) determiningthat the return power level is less than a second threshold, andrepeating steps a-b.
 22. A method comprising the steps of: a) measuringa return power level present at antennas of a modifiable mobilecommunication device at regular time intervals; b) determining that anoutput power of the modifiable mobile communication device is notgreater than a predefined specific absorption rate level; c)implementing mobile transmit diversity; and d) repeating steps a-c,until the output power of the modifiable mobile communication device isgreater than a predefined specific absorption rate level; e) determiningthat the return power level is greater than the first threshold,implementing a mobile transmit diversity algorithm combined withreflection-based beamforming, the reflection-based beamforming providingan adaptive beam shaping pattern that shapes a transmitted beam patternto minimize an amount of reflected transmitted power; f) re-measuringthe return power level; g) determining that the return power level hasincreased, and reducing the output power of the modifiable mobilecommunication device; h) determining that the return power level isequal to or greater than the second threshold, and repeating steps e-g,until the return power level is less than the second threshold.